U.S. patent number 10,609,320 [Application Number 15/955,132] was granted by the patent office on 2020-03-31 for photoelectric conversion device and method of driving photoelectric conversion device.
This patent grant is currently assigned to CANON KABUSHIKI KAISHA. The grantee listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Yukihiro Kuroda, Kazuhiro Saito, Yoshikazu Yamazaki.
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United States Patent |
10,609,320 |
Kuroda , et al. |
March 31, 2020 |
Photoelectric conversion device and method of driving photoelectric
conversion device
Abstract
A photoelectric conversion device includes a pixel region in
which pixels are arranged to form rows and columns, control lines
each connected to the pixels on a corresponding row, output lines
connected to the pixels on a corresponding column, a pixel control
unit configured to supply control signals to control the pixels for
the control lines, and a signal processing unit configured to
select and output a signal output to the output lines. The pixel
region includes readout regions each including a block of the
pixels arranged on continuous rows and columns, and at least one
row includes both of the pixel of the block forming a first readout
region and the pixel of the block forming a second readout region.
The pixel control unit and the signal processing unit are
configured to read out signals of the pixels in a corresponding
block sequentially for each of the readout regions.
Inventors: |
Kuroda; Yukihiro (Inagi,
JP), Yamazaki; Yoshikazu (Sagamihara, JP),
Saito; Kazuhiro (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
N/A |
JP |
|
|
Assignee: |
CANON KABUSHIKI KAISHA (Tokyo,
JP)
|
Family
ID: |
63916958 |
Appl.
No.: |
15/955,132 |
Filed: |
April 17, 2018 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20180316884 A1 |
Nov 1, 2018 |
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Foreign Application Priority Data
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|
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Apr 28, 2017 [JP] |
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|
2017-089437 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N
5/3745 (20130101); H04N 5/378 (20130101); H04N
5/23212 (20130101); H04N 5/3454 (20130101) |
Current International
Class: |
H04N
5/378 (20110101); H04N 5/3745 (20110101); H04N
5/345 (20110101); H04N 5/232 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2000-209509 |
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Jul 2000 |
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JP |
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2012-124800 |
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Jun 2012 |
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JP |
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Primary Examiner: Peterson; Christopher K
Attorney, Agent or Firm: Venable LLP
Claims
What is claimed is:
1. A photoelectric conversion device comprising: a pixel region in
which a plurality of pixels each including a photoelectric
converter are arranged to form a plurality of rows and a plurality
of columns; a plurality of control lines each connected to the
pixels arranged on a corresponding row of the plurality of rows; a
plurality of output lines each connected to the pixels arranged on
a corresponding column of the plurality of columns; a pixel control
unit connected to the plurality of control lines and configured to
supply control signals to control the pixels for the plurality of
control lines; and a signal processing unit connected to the
plurality of output lines and configured to select a signal output
to the plurality of output lines and output the selected signal,
wherein the pixel region includes a plurality of readout regions
each comprising a block of the pixels arranged on consecutive rows
and on consecutive columns, wherein at least one row of the
plurality of rows includes both of the pixel of the block forming a
first readout region of the plurality of readout regions and the
pixel of the block forming a second readout region of the plurality
of readout regions, wherein the signal processing unit is
configured to output signals of the pixels in a corresponding block
sequentially for each of the readout regions, wherein the pixel
control unit is configured to read out a signal of each of the
pixels of the block forming the second readout region to a
corresponding output line after reading out a signal of each of the
pixels of the block forming the first readout region to the
corresponding output line, and wherein, between a readout operation
of signals of the pixels of the block forming the first readout
region, which are arranged on the at least one row, and a readout
operation of signals of the pixels of the block forming the second
readout region, which are arranged on the at least one row, the
pixel control unit and the signal processing unit read out signals
of the pixels of the block forming the first readout region, which
are arranged on a row other than the at least one row.
2. The photoelectric conversion device according to claim 1,
wherein the pixel control unit and the signal processing unit are
configured to be able to switch readout order of the plurality of
readout regions.
3. The photoelectric conversion device according to claim 1,
wherein, out of the plurality of readout regions, a readout region
which is initially read out is a readout region including the
center of the pixel region.
4. The photoelectric conversion device according to claim 1,
wherein the plurality of readout regions include first readout
region including the center of the pixel region, and the second
readout region and a third readout region arranged in symmetrical
positions with respect to the center of the pixel region.
5. The photoelectric conversion device according to claim 4,
wherein the first readout region is wider than each of the second
readout region and the third readout region.
6. The photoelectric conversion device according to claim 4,
wherein the first readout region neighbors the second readout
region and the third readout region at respective boundaries.
7. The photoelectric conversion device according to claim 1,
wherein the control lines are arranged on each of the rows, the
number of the control lines being in accordance with the number of
the readout regions.
8. The photoelectric conversion device according to claim 1,
wherein the pixel control unit includes a plurality of first
scanning circuits associated with each of the plurality of readout
regions.
9. The photoelectric conversion device according to claim 1,
wherein the signal processing unit includes a plurality of second
scanning circuits associated with each of the plurality of readout
regions.
10. A method of driving a photoelectric conversion device that
includes a pixel region including a plurality of pixels arranged to
form a plurality of rows and a plurality of columns and each
including a photoelectric converter, a plurality of control lines
provided on respective ones of the plurality of rows and each
connected to the pixels arranged on a corresponding row of the
plurality of rows, and a plurality of output lines provided on
respective ones of the plurality of columns and each connected to
the pixels arranged on a corresponding column of the plurality of
columns, wherein a plurality of readout regions each formed of a
block of the pixels arranged on consecutive rows and on consecutive
columns are defined in the pixel region in which two or more of the
readout regions are arranged on at least one row of the plurality
of rows, a pixel control unit connected to the plurality of control
lines and configured to supply control signals to control the
pixels for the plurality of control lines, and a signal processing
unit connected to the plurality of output lines and configured to
select a signal output to the plurality of output lines and output
the selected signal the method comprising: scanning the control
lines to read out a signal of each of the pixels of the block
forming a first readout region to a corresponding output line;
scanning, after reading out the signals of the pixels of the block
forming the first readout region, the control lines to read out a
signal of each of the pixels of the block forming a second readout
regions to a corresponding output line, and scanning the output
lines associated with the readout regions and outputting signals of
the pixels in a corresponding block sequentially for each of the
readout regions, wherein, between a readout operation of signals of
the pixels of the block forming the first readout region, which are
arranged on the at least one row, and a readout operation of
signals of the pixels of the block forming the second readout
region, which are arranged on the at least one row, the pixel
control unit and the signal processing unit read out signals of the
pixels of the block forming the first readout region, which are
arranged on a row other than the at least one row.
11. The method of driving the photoelectric conversion device
according to claim 10, wherein the plurality of readout regions
include the first readout region including the center of the pixel
region, and the second readout region and a third readout region
arranged in symmetrical positions with respect to the center of the
pixel region, and wherein, out of the plurality of readout regions,
a readout region which is initially read out is the first readout
region.
12. An imaging system comprising: the photoelectric conversion
device according to claim 1; a solid-state imaging device that
outputs an optical image of an object as an image signal; a
calculation unit that calculates a distance to the object based on
an output signal of the photoelectric conversion device; and a
control unit that, based on the distance calculated by the
calculation unit, outputs a control signal that controls an optical
system so that the optical image of the object is focused on an
imaging plane of the solid-state imaging device.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a photoelectric conversion device
and a method of driving the same.
Description of the Related Art
X-Y address type photoelectric conversion devices having
two-dimensionally arranged photoelectric conversion elements have
been widely used as an imaging element of a single-lens reflex
digital camera or a video camera. In particular, CMOS photoelectric
conversion devices are suitable for higher integration or higher
functionality and thus used in other applications than image
capturing. As an example, a photoelectric conversion device that
performs signal readout suitable for automatic focus detection or
automatic exposure detection is known.
Japanese Patent Application Laid-Open No. 2000-209509 discloses a
solid-state imaging device that can selectively read out signals
from photoelectric conversion elements of a region required for
automatic exposure (AE) or automatic focus (AF). Further, Japanese
Patent Application Laid-Open No. 2012-124800 discloses an imaging
device that divides pixels to be read out into a plurality of
groups and performs readout on a group basis.
In the solid-state imaging device disclosed in Japanese Patent
Application Laid-Open No. 2000-209509, however, when signals from
photoelectric conversion elements of a plurality of regions are
read out and when these regions share rows, there is a limitation
in high speed readout of a particular region because selection and
readout of rows are simultaneously performed. Further, it is not
possible to control accumulation of the photoelectric conversion
elements on a region basis. Further, in the imaging device
disclosed in Japanese Patent Application Laid-Open No. 2012-124800,
while readout is performed on a divided-group basis, no
consideration has been made for a case where these groups share
rows.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a photoelectric
conversion device and a method of driving the same that can improve
flexibility in setting of readout regions within a pixel region and
controllability of readout on a readout region basis.
According to an aspect of the present invention, there is provided
a photoelectric conversion device including a pixel region in which
a plurality of pixels each including a photoelectric converter are
arranged to form a plurality of rows and a plurality of columns, a
plurality of control lines each connected to the pixels arranged on
a corresponding row of the plurality of rows, a plurality of output
lines each connected to the pixels arranged on a corresponding
column of the plurality of columns, a pixel control unit connected
to the plurality of control lines and configured to supply control
signals to control the pixels for the plurality of control lines,
and a signal processing unit connected to the plurality of output
lines and configured to select a signal output to the plurality of
output lines and output the selected signal, wherein pixel region
includes a plurality of readout regions each comprising a block of
the pixels arranged on continuous rows and continuous columns,
wherein at least one row of the plurality of rows includes both of
the pixel of the block forming a first readout region of the
plurality of readout regions and the pixel of the block forming a
second readout region of the plurality of readout regions, and
wherein the pixel control unit and the signal processing unit are
configured to read out signals of the pixels in a corresponding
block sequentially for each of the readout regions.
According to another aspect of the present invention, there is
provided a method of driving a photoelectric conversion device that
includes a pixel region including a plurality of pixels arranged to
form a plurality of rows and a plurality of columns and each
including a photoelectric converter, a plurality of control lines
provided on respective of the plurality of rows and each connected
to the pixels arranged on a corresponding row of the plurality of
rows, and a plurality of output lines provided on respective of the
plurality of columns and each connected to the pixels arranged on a
corresponding column of the plurality of columns, wherein a
plurality of readout regions each formed of a block of the pixels
arranged on continuous rows and on continuous columns are defined
in the pixel region in which two or more of the readout regions are
arranged on at least one row of the plurality of rows, the method
includes scanning the control lines and the output lines associated
with the readout regions and reading out signals of the pixels in a
corresponding block sequentially for each of the readout
regions.
Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a general configuration of a
photoelectric conversion device according to a first
embodiment.
FIG. 2 is a circuit diagram illustrating a configuration example of
pixels of the photoelectric conversion device according to the
first embodiment.
FIG. 3A, FIG. 3B and FIG. 3C are schematic diagrams illustrating a
method of driving the photoelectric conversion device according to
the first embodiment.
FIG. 4A, FIG. 4B and FIG. 4C are schematic diagrams illustrating a
photoelectric conversion device and a method of driving the same
according to a second embodiment.
FIG. 5 is a block diagram illustrating a configuration example of
respective units of the photoelectric conversion device according
to the second embodiment.
FIG. 6 is a diagram illustrating a configuration example of a pixel
region of the photoelectric conversion device according to the
second embodiment.
FIG. 7 is a block diagram illustrating a general configuration of
an imaging system according to a third embodiment.
DESCRIPTION OF THE EMBODIMENTS
Preferred embodiments of the present invention will now be
described in detail in accordance with the accompanying
drawings.
First Embodiment
A photoelectric conversion device and a method of driving the same
according to a first embodiment of the present invention will be
described with reference to FIG. 1 to FIG. 3C.
FIG. 1 is a block diagram illustrating a general configuration of
the photoelectric conversion device according to the present
embodiment. FIG. 2 is a circuit diagram illustrating a
configuration example of pixels of the photoelectric conversion
device according to the present embodiment. FIG. 3A to FIG. 3C are
schematic diagrams illustrating the method of driving the
photoelectric conversion device according to the present
embodiment.
As illustrated in FIG. 1, a photoelectric conversion device 100
according to the present embodiment includes a pixel region 10, a
row select circuit 20, a readout circuit 30, a column select
circuit 40, an output circuit 50, and a control circuit 60.
In the pixel region 10, a plurality of pixels P arranged in a
matrix over a plurality of rows by a plurality of columns are
provided. Each of the pixels P includes a photoelectric conversion
element that converts an incident light into charges in accordance
with the light amount thereof. The number of rows and the number of
columns of a pixel array arranged in the pixel region 10 are not
limited in particular.
A control line 14 is arranged on each row of the pixel array of the
pixel region 10 and extends in the row direction (horizontal
direction in FIG. 1). The control line 14 is connected to the
pixels P aligned in the row direction to form a signal line common
to these pixels P. Further, an output line 16 is arranged on each
column of the pixel array of the pixel region 10 and extends in the
column direction (vertical direction in FIG. 1). The output line is
connected to the pixels P aligned in the column direction to form a
signal line common to these pixels P, respectively.
The control lines 14 on respective rows are connected to the row
select circuit 20. The row select circuit 20 is a drive circuit
that supplies, to the pixels P via the control lines 14 provided on
a row basis of the pixel array, control signals for driving the
readout circuit within the pixels P when reading out signals from
respective pixels P. The row select circuit 20 can be configured
using a shift resistor or an address decoder. Signals read out from
the pixels P are input to the readout circuit 30 via the output
lines 16 provided on a column basis of the pixel array.
The readout circuit 30 is a circuit unit that performs a
predetermined process, for example, a correlated double sampling
(CDS) process or signal processing such as an amplification process
on signals read out from the pixels P. The readout circuit 30 may
include signal holding units, CDS circuits, column amplifiers, or
the like.
The column select circuit 40 is a circuit unit that supplies, to
the readout circuit 30, control signals used for transferring
signals processed in the readout circuit 30 to the output circuit
50 sequentially on a column basis. The column select circuit 40 can
be configured using a shift resistor or an address decoder. The
output circuit 50 is a circuit unit that is formed of a buffer
amplifier or a differential amplifier to amplify and output a
signal on a column selected by the column select circuit 40.
Note that, in the present specification, the row select circuit 20
may be referred to as a pixel control unit in focusing the
functionality thereof. Further, the readout circuit 30, the column
select circuit 40, and the output circuit 50 may be collectively
referred to as a signal processing unit.
The control circuit 60 is a circuit unit that supplies control
signals to the row select circuit 20, the readout circuit 30, and
the column select circuit 40 to control the operation or the timing
thereof. Some or all of the control signals supplied to the row
select circuit 20, the readout circuit 30, and the column select
circuit 40 may be supplied from the outside of the photoelectric
conversion device 100.
FIG. 2 is a circuit diagram illustrating an example of pixel
circuits forming the pixel region 10. While FIG. depicts nine
pixels P arranged in three rows by three columns out of the pixels
P forming the pixel region 10, the number of pixels P forming the
pixel region 10 is not limited in particular.
Each of the plurality of pixels P includes a photoelectric
converter PD, transfer transistors M1 and M2, a reset transistor
M3, an amplifier transistor M4, a select transistor M5, and an
overflow transistor M6. The photoelectric converter PD is a
photodiode, for example. The anode of the photodiode of the
photoelectric converter PD is connected to a ground voltage line,
and the cathode is connected to the source of the transfer
transistor M1 and the source of the overflow transistor M6. The
drain of the transfer transistor M1 is connected to the source of
the transfer transistor M2. The connection node of the drain of the
transfer transistor M1 and the source of the transfer transistor M2
includes a capacitance component and forms a charge holding portion
C1. In FIG. 2, the holding portion C1 is represented as a
capacitor, one terminal of which is connected to the node. The
other terminal of the capacitor forming the holding portion C1 is
grounded.
The drain of the transfer transistor M2 is connected to the source
of the reset transistor M3 and the gate of the amplifier transistor
M4. The connection node of the drain of the transfer transistor M2,
the source of the reset transistor M3, and the gate of the
amplifier transistor M4 is a so-called floating diffusion (FD)
portion. The FD portion includes a capacitance component (floating
diffusion capacitor) and forms a charge holding unit C2. In FIG. 2,
the holding portion C2 is represented as a capacitor, one terminal
of which is connected to the FD portion. The other terminal of the
capacitor forming the holding portion C2 is grounded.
The drain of the reset transistor M3, the drain of the amplifier
transistor M4, and the drain of the overflow transistor M6 are
connected to a power source voltage line (VDD). Note that any two
or three of a voltage supplied to the drain of the reset transistor
M3, a voltage supplied to the drain of the amplifier transistor M4,
and a voltage supplied to the drain of the overflow transistor M6
may be the same, or all of the above may be different. The source
of the amplifier transistor M4 is connected to the drain of the
select transistor M5. The source of the select transistor M5 is
connected to the output line 16.
In the case of the pixel configuration of FIG. 2, each of the
control lines 14 arranged in the pixel region 10 includes signal
lines TX1, TX2, OFG, RES, and SEL. The signal line TX1 is connected
to the gates of the transfer transistors M1 of the pixels P
belonging to the corresponding row, respectively, and forms a
signal line common to these pixels P. The signal line TX2 is
connected to the gates of the transfer transistors M2 of the pixels
P belonging to the corresponding row, respectively, and forms a
signal line common to these pixels P. The signal line RES is
connected to the gates of the reset transistors M3 of the pixels P
belonging to the corresponding row, respectively, and forms a
signal line common to these pixels P. The signal line SEL is
connected to the gates of the select transistors M5 of the pixels P
belonging to the corresponding row, respectively, and forms a
signal line common to these pixels P. The signal line OFG is
connected to the gates of the overflow transistors M6 of the pixels
P belonging to the corresponding row, respectively, and forms a
signal line common to these pixels P. Note that, in FIG. 2, the
corresponding row number is provided to the name of each control
line (for example, TX1(n-1), TX1(n), TX1(n+1)).
A control signal that is a drive pulse for controlling the transfer
transistor M1 is output to the signal line TX1 from the row select
circuit 20. A control signal that is a drive pulse for controlling
the transfer transistor M2 is output to the signal line TX2 from
the row select circuit 20. A control signal that is a drive pulse
for controlling the reset transistor M3 is output to the signal
line RES from the row select circuit 20. A control signal that is a
drive pulse for controlling the select transistor M5 is output to
the signal line SEL from the row select circuit 20. A control
signal that is a drive pulse for controlling the overflow
transistor M6 is output to the signal line OFG from the row select
circuit 20. When each transistor is formed of an n-channel
transistor, the corresponding transistor is turned on when supplied
with a high-level control signal from the row select circuit 20.
Further, the corresponding transistor is turned off when supplied
with a low-level control signal from the row select circuit 20.
The output line 16 arranged on each column of the pixel region 10
is connected to the sources of the select transistors M5 of the
pixels P aligned in the column direction, respectively, and forms a
signal line common to these pixels P. Note that the select
transistor M5 of the pixel P may be omitted. In this case, the
output line 16 is connected to the sources of the amplifier
transistors M4. A current source 18 is connected to each of the
output lines 16.
The photoelectric converter PD converts (photoelectrically
converts) an incident light into charges in accordance with the
light amount thereof and accumulates the generated charges. The
overflow transistor M6 resets the photoelectric converter PD to a
predetermined potential in accordance with the voltage of the power
source voltage line. The transfer transistor M1 transfers charges
held in the photoelectric converter PD to the holding portion C1.
The holding portion C1 holds charges generated by the photoelectric
converter PD in a different location from the photoelectric
converter PD. The transfer transistor M2 transfers charges held in
the holding portion C1 to the holding portion C2. The holding
portion C2 holds charges transferred from the holding portion C1
and sets the voltage of the FD portion, which is also the input
node of the amplifier unit (the gate of the amplifier transistor
M4), to a voltage in accordance with the capacitance of the holding
portion C2 and the amount of the transferred charges. The reset
transistor M3 is a reset unit that resets the holding portion C2 to
a predetermined potential in accordance with the voltage of the
power source voltage line. The select transistor M5 selects the
pixels P which output signals to the output lines 16. In the
amplifier transistor M4, the drain is supplied with the power
source voltage, and the source is supplied with a bias current from
the current source 18 via the select transistor M5, which forms an
amplifier unit (source follower circuit) whose gate is the input
node. Thereby, the amplifier transistor M4 outputs a signal VOUT
based on charges generated by an incident light to the output line
16. Note that, in FIG. 2, the corresponding column number is
provided to the signal Vout (for example, Vout(m-1), Vout(m),
Vout(m+1)).
According to the pixel configuration illustrated in FIG. 2, charges
generated by the photoelectric converter PD while the holding
portion C1 is holding charges can be accumulated in the
photoelectric converter PD. This enables an imaging operation such
that exposure periods are matched among the plurality of pixels P,
namely, a so-called global electronic shutter operation. Note that
electronic shutter means electrically controlling accumulation of
charges generated by an incident light.
Next, the method of driving the photoelectric conversion device of
the present embodiment will be described by using FIG. 3A to FIG.
3C.
FIG. 3A is a diagram illustrating a configuration example of the
pixel region 10 of the photoelectric conversion device according to
the present embodiment. While a case where the pixel region 10 is
formed of a plurality of pixels P arranged in a matrix of five rows
by eight columns will be described as an example here, the number
of pixels P forming the pixel region 10 is not limited in
particular. In FIG. 3A, each pixel P is represented by a reference
of the reference P appended with a row number and a column number.
For example, the pixel at the first row and the first column is
denoted as the pixel P11, the pixel at the third row and the first
column is denoted as the pixel P31, and the pixel at the fifth row
and the eighth column is denoted as the pixel P58. Note that, in
FIG. 3A, depiction of the readout circuit 30, the output circuit
50, the control circuit 60, and the like is omitted for simplified
illustration.
In the method of driving the photoelectric conversion device
according to the present embodiment, pixel signals are read out
separately from two readout regions (a first readout region 72 and
a second readout region 74) defined within the pixel region 10, as
illustrated in FIG. 3A. Each of the first readout region 72 and the
second readout region 74 is formed of a block comprising a pixel
array with continuous rows and columns. FIG. 3A illustrates an
example with a case where each of the first readout region 72 and
the second readout region 74 is formed of a block comprising a
pixel array of three rows by two columns.
The first readout region 72 is a region of the fourth column to the
fifth column on the second row to the fourth row. Here, the second
row to the fourth row corresponding to positions in the vertical
direction of the first readout region 72 is defined as a first
vertical region, and the fourth column to the fifth column
corresponding to positions in the horizontal direction of the first
readout region 72 is defined as a first horizontal region. Also,
the second readout region 74 is a region of the seventh column to
the eighth column on the first row to the third row. Here, the
first row to the third row corresponding to positions in the
vertical direction of the second readout region 74 is defined as a
second vertical region, and the seventh column to the eighth column
corresponding to positions in the horizontal direction of the
second readout region 74 is defined as a second horizontal
region.
As illustrated in FIG. 3A, while there is no overlapping part
between the first horizontal region and the second horizontal
region, there is an overlapping part between the first vertical
region and the second vertical region. That is, both the first
readout region 72 and the second readout region 74 include the
second row and the third row. In other words, two or more readout
regions are arranged on at least one row of the plurality of rows
forming the pixel region 10. Alternatively, both of pixels of a
block forming the first readout region of the plurality of readout
regions and pixels of a block forming the second readout region of
the plurality of readout regions are included in at least one row
of the plurality of rows forming the pixel region 10.
The row select circuit 20 and the column select circuit 40 are
configured to be able to selectively read out pixel signals of the
pixels P belonging to the first readout region 72 and pixel signals
of the pixels P belonging to the second readout region 74.
For example, when the row select circuit 20 is configured using a
decoder, the control line 14 on the rows associated with either the
first readout region 72 or the second readout region 74 can be
selectively driven in accordance with input address information.
Further, when the row select circuit 20 is configured using a shift
resistor, a row select circuit associated with the first readout
region 72 and a row select circuit associated with the second
readout region 74 can be provided. In any cases, the control line
14 connected to the pixels P of the first readout region 72 and the
control line 14 connected to the pixels P of the second readout
region 74 are arranged on at least the rows (the second row and the
third row) belonging to both the first readout region 72 and the
second readout region 74.
Similarly, when the column select circuit 40 is configured using a
decoder, signals of the columns associated with either the first
readout region 72 or the second readout region 74 can be
selectively output in accordance with input address information.
Further, when the column select circuit 40 is configured using a
shift resistor, a column select circuit associated with the first
readout region 72 and a column select circuit associated with the
second readout region 74 can be provided. When there is an
overlapping part between the first horizontal region and the second
horizontal region, two output lines 16 may be arranged on the
overlapping column in a similar manner to the case of the control
line 14.
With such a configuration of the row select circuit and the column
select circuit 40, it is possible to independently control the
exposure periods or control the readout operations of pixel signals
for the pixels P belonging to the first readout region 72 and the
pixels P belonging to the second readout region 74. Further, it is
possible to separately output pixel signals of the pixels P
belonging to the first readout region 72 and pixel signals of the
pixels P belonging to the second readout region 74. Further, any
order of performing the readout of pixel signals of the pixels P
belonging to the first readout region 72 and the readout of pixel
signals of the pixels P belonging to the second readout region 74
may be set.
FIG. 3B and FIG. 3C are conceptual diagrams illustrating the order
of output signals SOUT output from the photoelectric conversion
device 100 in a temporal manner. In FIG. 3B and FIG. 3C, each of
S24, S25, S34, . . . represents the output signal SOUT output from
corresponding one of the pixels P. For example, the output signal
S24 is the output signal SOUT output from the pixel P24, the output
signal S25 is the output signal SOUT output from the pixel P25, and
the output signal S34 is the output signal SOUT output from the
pixel P34.
FIG. 3B illustrates a case where pixel signals of the pixels P of
the first readout region 72 are selectively read out first, and
pixel signals of the pixels P of the second readout region 74 are
then selectively read out. In the first readout region 72 and the
second readout region 74, readout is sequentially performed on a
row basis, and the output signals S24, S25, S34, S35, S44, S45,
S17, S18, S27, S28, S37, and S38 are output in this order from the
photoelectric conversion device 100.
FIG. 3C illustrates a case where pixel signals of the pixels P of
the second readout region 74 are selectively read out first, and
pixel signals of the pixels P of the first readout region 72 are
then selectively read out, in the opposite manner to the case of
FIG. 3B. In this case, the output signals S17, S18, S27, S28, S37,
S38, S24, S25, S34, S35, S44, and S45 are output in this order from
the photoelectric conversion device 100.
In the present embodiment, the row select circuit 20 and the column
select circuit 40 are configured to be able to selectively read out
image signals of the pixels P in designated readout regions within
the pixel region 10 and output the pixel signals from the
photoelectric conversion device 100 in a temporal manner on a
readout region basis. Therefore, as in the case of the first
vertical region and the second vertical region of the first readout
region 72 and the second readout region 74, even when vertical
regions of readout regions overlap with each other, pixel signals
can be output on a readout region basis. Thereby, in applications
such as, for example, automatic focus detection that require
calculation processing of output signals on a readout region basis,
faster operation processing is allowed compared to the case where
signal output of a plurality of readout regions sharing rows is
performed in a time division manner.
Further, the row select circuit 20 and the column select circuit 40
are configured to be able to switch the readout order of readout
regions, as illustrated in FIG. 3B and FIG. 3C. Thereby, a readout
region on which operation processing of an output signal is
intended to be performed with priority can be initially read out,
which enables faster operation processing.
As discussed above, according to the present embodiment,
flexibility in setting of readout regions within a pixel region and
controllability of readout on a readout region basis can be
improved, which enables faster readout of pixels in a particular
readout region.
Second Embodiment
A photoelectric conversion device and a method of driving the same
according to a second embodiment of the present invention will be
described with reference to FIG. 4A to FIG. 6. Components similar
to those of the photoelectric conversion device and the drive
method thereof according to the first embodiment illustrated in
FIG. 1 to FIG. 3C are labeled with the same reference, and the
description thereof will be omitted or simplified. FIG. 4A to FIG.
4C are schematic diagrams illustrating the photoelectric conversion
device and the method of driving the same according to the present
embodiment. FIG. 5 is a block diagram illustrating a configuration
example of respective units of the photoelectric conversion device
according to the present embodiment. FIG. 6 is a diagram
illustrating a configuration example of a pixel region of the
photoelectric conversion device according to the present
embodiment.
In the present embodiment, another method of driving the
photoelectric conversion device according to the first embodiment
will be described. In the method of driving the photoelectric
conversion device according to the present embodiment, pixel
signals are separately read out from three readout regions (the
first readout region 72, the second readout region 74, and a third
readout region 76) defined within the pixel region 10, as
illustrated in FIG. 4A. Each of the first readout region 72, the
second readout region 74, and the third readout region 76 is formed
of a block comprising a pixel array with continuous rows and
columns. FIG. 4A illustrates an example with a case where the first
readout region 72 is formed of a block comprising a pixel array of
five rows by four columns, and each of the second readout region 74
and the third readout region 76 is formed of a block comprising a
pixel array of three rows by two columns.
The first readout region 72 is a region of the third column to the
sixth column on the first row to the fifth row. Here, the first row
to the fifth row corresponding to positions in the vertical
direction of the first readout region 72 is defined as a first
vertical region, and the third column to the sixth column
corresponding to positions in the horizontal direction of the first
readout region 72 is defined as a first horizontal region.
The second readout region 74 is a region of the seventh column to
the eighth column on the second row to the fourth row. Here, the
second row to the fourth row corresponding to positions in the
vertical direction of the second readout region 74 is defined as a
second vertical region, and the seventh column to the eighth column
corresponding to positions in the horizontal direction of the
second readout region 74 is defined as a second horizontal
region.
The third readout region 76 is a region of the first column to the
second column on the second row to the fourth row. Here, the first
column to the second column corresponding to positions in the
horizontal direction of the third readout region 76 is defined as a
third horizontal region. The second row to the fourth row
corresponding to positions in the vertical direction of the third
readout region 76 are the same as the second vertical region of the
second readout region 74.
As illustrated in FIG. 4A, while there is no overlapping part among
the first horizontal region, the second horizontal region, and the
third horizontal region, there is an overlapping part between the
first vertical region and the second vertical region. That is, all
the first readout region 72, the second readout region 74, and the
third readout region 76 include the second row to the fourth
row.
FIG. 4B is a diagram illustrating the positional relationship among
the first readout region 72, the second readout region 74, and the
third readout region 76 in the pixel region 10. The first readout
region 72 is arranged such that the center thereof matches the
center of the pixel region 10. The first readout region 72 is
larger than each of the second readout region 74 and the third
readout region 76. Further, the second readout region 74 and the
third readout region 76 are arranged so as to be symmetrical with
respect to a line in the vertical direction (up-down direction in
FIG. 4B) passing through the center of the pixel region 10. The
first readout region 72 is adjacent to the second readout region 74
and the third readout region 76.
FIG. 4C is a conceptual diagram illustrating the order of the
output signals SOUT in a temporal manner that are output from the
photoelectric conversion device 100. In this example, pixel signals
of the pixels P of the first readout region 72 is selectively read
out first, pixel signals of the pixels P of the second readout
region 74 are then selectively readout, and pixel signals of the
pixels P of the third readout region 76 are then selectively
readout. In this case, output signals are output from the
photoelectric conversion device 100 in the order of S13, S14, . . .
, S16, S23, . . . , S56, S27, S28, S37, . . . , S48, S21, S31, . .
. , and S42.
FIG. 5 is a block diagram illustrating a configuration example of
the photoelectric conversion device 100 for implementing the drive
method of FIG. 4A to FIG. 4C. In FIG. 5, illustration of the pixels
P in the pixel region 10 is omitted, and only the first readout
region 72, the second readout region 74, and the third readout
region 76 are illustrated. The row select circuit 20 has a first
row select circuit 22, a second row select circuit 24, and a third
row select circuit 26. Each of the first row select circuit 22, the
second row select circuit 24, and the third row select circuit 26
has a function of a vertical scanning circuit. Further, the column
select circuit 40 has a first column select circuit 42, a second
column select circuit 44, and a third column select circuit 46.
Each of the first column select circuit 42, the second column
select circuit 44, and the third column select circuit 46 has a
function of a horizontal scanning circuit.
The first row select circuit 22 is a pixel control unit that
controls the exposure period or the readout operation of pixel
signals of the pixels P belonging to the first readout region 72 on
a row basis. The second row select circuit 24 is a pixel control
unit that controls the exposure period or the readout operation of
pixel signals of the pixels P belonging to the second readout
region 74 on a row basis. The third row select circuit 26 is a
pixel control unit that controls the exposure period or the readout
operation of pixel signals of the pixels P belonging to the third
readout region 76 on a row basis.
The first column select circuit 42 is a signal processing unit that
sequentially selects columns belonging to the first readout region
72 and outputs pixel signals. The second column select circuit 44
is a signal processing unit that sequentially selects columns
belonging to the second readout region 74 and outputs pixel
signals. The third column select circuit 46 is a signal processing
unit that sequentially selects columns belonging to the third
readout region 76 and outputs pixel signals.
FIG. 6 is a schematic diagram illustrating an example of the
connection relationship between the row select circuit 20 and the
pixels P. As illustrated in FIG. 6, the control line 14 on each row
includes a set of three control lines 141, 142, and 143
corresponding to the number of readout regions. The control line
141 is the control line 14 connected to the pixels P belonging to
the first readout region 72. The control line 141 is connected to
the first row select circuit 22 and supplied with various control
signals used for driving the pixels P from the first row select
circuit 22. The control line 142 is the control line 14 connected
to the pixels P belonging to the second readout region 74. The
control line 142 is connected to the second row select circuit 24
and supplied with various control signals used for driving the
pixels P from the second row select circuit 24. The control line
143 is the control line 14 connected to the pixels P belonging to
the third readout region 76. The control line 143 is connected to
the third row select circuit 26 and supplied with various control
signals used for driving the pixels P from the third row select
circuit 26.
With such a configuration of the row select circuit and the column
select circuit 40, it is possible to independently control the
pixels P belonging to the first readout region 72, the pixels P
belonging to the second readout region 74, and the pixels P
belonging to the third readout region 76. Further, it is possible
to separately output pixel signals of the pixels P belonging to the
first readout region 72, pixel signals of the pixels P belonging to
the second readout region 74, and pixel signals of the pixels P
belonging to the third readout region 76. Thereby, a readout region
on which processing of an output signal is intended to be performed
with priority can be initially read out, which enables faster
processing.
Further, with a focus detection device being configured using the
photoelectric conversion device according to the present
embodiment, it is possible to increase the focus detection speed
while improving the focus detection accuracy. For example, at least
a pair of focus detection regions that output focus detection
signals including parallax information are arranged in any of the
plurality of readout regions. By reading out this readout region
earlier than other readout regions, it is possible to shorten the
time before the completion of the readout of signals used for focus
detection and start focus detection calculation at an earlier
timing compared to the case where all the pixels P are read out
sequentially on a row basis. This enables quick feedback to
automatic focus adjustment of the image capture lens or the
like.
Note that, while the row select circuit 20 and the column select
circuit 40 are formed of three circuits, respectively, when the row
select circuit 20 and the column select circuit 40 are assumed to
be configured using a shift resistor in the example of FIG. 5, the
row select circuit 20 and the column select circuit 40 may be
formed of a single circuit by using a decoder, respectively.
In the present embodiment, the row select circuit 20 and the column
select circuit 40 are configured to be able to selectively read out
pixel signals of the pixels P of three designated readout regions
within the pixel region and output the pixel signals from the
photoelectric conversion device 100 in a temporal manner on a
readout region basis. In general, since a capturing object is more
frequently captured near the center of the frame in the imaging
device, the arrangement of the first readout region 72, the second
readout region 74, and the third readout region 76 as described
above is suitable for signal processing of electronic zooming or
the like. Further, the symmetry of the second readout region 74 and
the third readout region 76 is suitable for signal processing of
automatic focus detection or automatic exposure detection, for
example. Further, since respective readout regions are neighbored
at the boundary thereof, there is no need for a circuit such as
dummy or a layout region in the column select circuit 40, which
allows for a simple configuration.
As discussed above, according to the present embodiment,
flexibility in setting of readout regions within a pixel region and
controllability of readout on a readout region basis can be
improved, which enables faster readout of pixels in a particular
readout region.
Third Embodiment
An imaging system according to a third embodiment of the present
invention will be described with reference to FIG. 7. Components
similar to those of the photoelectric conversion devices according
to the first and second embodiments illustrated in FIG. 1 to FIG. 6
are labeled with the same reference, and the description thereof
will be omitted or simplified. FIG. 7 is a block diagram
illustrating a configuration example of the imaging system
according to the present embodiment.
As illustrated in FIG. 7, an imaging system 200 according to the
present embodiment has a barrier 201, a lens 202, an aperture 203,
a solid-state imaging device 204, and an AF sensor 205. The lens
202 is an optical system for capturing an optical image of an
object. The barrier 201 protects the lens 202. The aperture 203
adjusts the light amount of a light passing through the lens 202.
The solid-state imaging device 204 acquires an optical image of an
object captured by the lens 202 as an image signal. The AF sensor
205 is a focus detection device configured using the photoelectric
conversion device 100 described in the second embodiment.
The imaging system 200 further has an analog signal processing
device 206, an A/D converter 207, and a digital signal processing
unit 208. The analog signal processing device 206 processes signals
output from the solid-state imaging device 204 and the AF sensor
205. The A/D converter 207 performs analog-to-digital conversion on
a signal output from the analog signal processing device 206. The
digital signal processing unit 208 performs various correction on
image data output from the A/D converter 207 or performs a process
of compressing data.
The imaging system 200 further has a memory unit 209, an external
I/F circuit 210, a timing generation unit 211, a general
control/operation unit 212, and a storage medium control I/F unit
213. The memory unit 209 temporarily stores image data. The
external I/F circuit 210 communicates with an external device such
as an external computer 215. The timing generation unit 211 outputs
various timing signals to the digital signal processing unit 208 or
the like. The general control/operation unit 212 controls various
calculation and the entire camera. The storage medium control I/F
unit 213 exchanges data with a removable storage medium 214 such as
a semiconductor memory used for storing the acquired image data or
performing readout of image data.
When the barrier 201 is opened, an optical image from an object
enters the AF sensor 205 via the lens 202 and the aperture 203. The
general control/operation unit 212 calculates the distance to an
object by using the above-described phase difference detection
based on an output signal from the AF sensor 205. The general
control/operation unit 212 then performs autofocus control to drive
the lens 202 based on a calculation result, again determine whether
or not focused on an imaging plane, and again drive the lens 202
when determined to be out of focus.
Subsequently, after confirmed to be focused, a charge accumulation
operation by the solid-state imaging device 204 is started. Upon
the completion of the charge accumulation operation of the
solid-state imaging device 204, an image signal output from the
solid-state imaging device 204 is subjected to a predetermined
process in the analog signal processing device 206 and then
digitally converted by the A/D converter 207. The digitally
converted image signal is written to the memory unit 209 by the
general control/operation unit 212 via the digital signal
processing unit 208.
Then, data accumulated in the memory unit 209 is stored in the
storage medium 214 via the storage medium control I/F unit 213 by
the general control/operation unit 212. Alternatively, data
accumulated in the memory unit 209 may be input directly to the
external computer 215 via the external I/F circuit 210.
As described in the first and second embodiments, by configuring
the AF sensor 205 using the photoelectric conversion device 100
illustrated in any of the above embodiments, it is possible to
increase the focus detection speed while improving the focus
detection accuracy. Therefore, according to the imaging system of
the present embodiment using such the AF sensor 205, a
higher-definition image can be acquired quickly.
MODIFIED EMBODIMENTS
The present invention is not limited to the above-described
embodiments, and various modifications are possible.
For example, an example in which a part of the configuration of any
of the embodiments is added to another embodiment or an example in
which a part of the configuration of any of the embodiments is
replaced with a part of the configuration of another embodiment is
one of the embodiments of the present invention.
Further, in the photoelectric conversion devices 100 in the first
and second embodiments, the pixel circuit forming each of the
pixels P is not limited to that illustrated in FIG. 2. For example,
the pixel P is not necessarily required to have the configuration
supporting a global electronic shutter operation, and the transfer
transistor M2 and the overflow transistor M6 may not be provided.
In this case, charges accumulated in the photoelectric converter PD
are transferred from the transfer transistor M1 to the FD portion
(holding portion C2).
Further, while an example of the photoelectric conversion device in
which two or three readout regions are defined within the pixel
region 10 has been described in the first and second embodiments,
the number of readout regions defined within the pixel region 10 is
not limited in particular.
Further, the imaging system illustrated in the third embodiment
described above illustrates an example of an imaging system to
which the photoelectric conversion device of the present invention
can be applied, imaging systems to which the photoelectric
conversion device of the present invention can be applied is not
limited to the configuration illustrated in FIG. 7. The intended
use of the photoelectric conversion device is not limited to the AF
sensor, but also can be applied to an AE sensor or the like.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2017-089437, filed Apr. 28, 2017, which is hereby incorporated
by reference herein in its entirety.
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